Bearings are typically used in various rotating devices such as motors to support a rotating shaft in a frame. Typically, two identical bearings are positioned on opposing ends of the shaft with a respective inner ring of each bearing secured to the shaft and a respective outer ring of each bearing secured to the frame. A plurality of balls are typically positioned between the inner ring and outer ring of each bearing. Such motors are often installed with the shaft in a horizontal position. Typically, the shaft, the inner rings, the outer rings and the balls are manufactured from an iron based alloy such as a bearing grade alloy steel. Such motors are often operated at normal ambient temperatures or close thereto.
However, some motors are installed with the shaft in a vertical position and are operated in an oscillatory manner. Some motors are required to operate under extreme hot to cold temperature ranges. In addition, in certain applications, weight reduction is important and light-weight materials such as aluminum may be employed for the shaft and/or frame. However, the bearings are typically made from an iron based alloy (e.g., steel) to maintain adequate load carrying performance. Use of different metallic materials for the bearings, shaft and frame in vertical shaft installations make it difficult to maintain operating torque in an acceptable predetermined range at the extreme temperature ranges due to differences in coefficients of thermal expansion between the bearings, shaft and frame.
Based on the foregoing, there is a need for an improved bearing system capable of operating at an acceptable operating torque under the foregoing conditions.